RESUMEN
The etiology of strabismus has long been observed to have a genetic component. Since strabismus is one of the major causes of an amblyobia, early detection and treatment is essential for restoration of proper alignment of the visual axes and establishment of binocular vision. We examined 100 patients with strabismus, 50 males and 50 females, attending the Research Institute of Ophthalmology, aiming to study the heritability and different factors predispose to strabismus for early intervention. Patients under study were submitted to full history taking, family pedigree construction, complete clinical examination, including eye evaluation, and cytogenetic study of the peripheral blood lymphocytes when indicated. Patients with strabismus were classified into two groups. The first group included 76 patients with esotropia [76%], winch subclassified into two groups: Isolated group [72%], included 66 patients with infantile esotropia [66%], 5 patients with Duane syndrome [5%], and 1 patient with congenital ocular fibrosis [1%]. And associated group [strabismus is a component of a genetic syndrome] which included 4 [4%] patients with Mobius syndrome. The second group included 24 [24%] patients with isolated exotropia. Our study revealed that heritability plays an important role in development of strabismus. Also low birth weight is an important risk factor. So young infants in families at high risk for developing strabismus, and low birth weight infants should be screened for early detection, better intervention and therapeutic trials, this allow normal development of binocular vision, depth perception, and prevent psychosocial dysfunction. There is limited evidence in support of an environmental causes of strabismus